20,746 research outputs found

    Hybrid Quasicrystals, Transport and Localization in Products of Minimal Sets

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    We consider convex combinations of finite-valued almost periodic sequences (mainly substitution sequences) and put them as potentials of one-dimensional tight-binding models. We prove that these sequences are almost periodic. We call such combinations {\em hybrid quasicrystals} and these studies are related to the minimality, under the shift on both coordinates, of the product space of the respective (minimal) hulls. We observe a rich variety of behaviors on the quantum dynamical transport ranging from localization to transport.Comment: 3 figures. To appear in Journal of Stat. Physic

    Dissipative quantum systems modeled by a two level reservoir coupling

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    The coupling between a quantum dynamical system and a two-level system reservoir is analysed within the framework of the Feynman-Vernon theory. We stress the differences between this new reservoir and the well-known bath of oscillators and show that, in order to obtain the Langevin equation for the system of interest in the high temperature regime, we have to choose a spectral distribution function J(ω)J(\omega) which is finite for ω=0\omega=0.Comment: 6 pages, RevteX, preprint UNICAM

    Análise econômica da adoção da mecanização e adubação na cultura de arroz e caupi em Altamira - Pará.

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    Avaliação preliminar do desempenho operacional e econômico de dois tipos de colheitadeira de algodão.

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    bitstream/CNPA-2009-09/18299/1/CIRTEC39.pdfProdução Científica
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